I feel like Signy will find Ashya rather fascinating--probably because in a lot of ways, she seems to be very much a teenage girl (all that mischief, and flirting with Templars just cracks me up no matter what! hahaha), and Signy has a lot of that personality left over--what hasn't been squashed by abominations and exile and other forms of unpleasantness, at least. Although she was... more girlish, and less outgoing, I suppose. And... I really can't say what her opinion on blood magic would be. Since she wasn't raised with any real concept of "evil magic" versus "good magic"; just "surfacer magic".
Add to that, someone else who can answer her questions about being a mage and the Fade and magic and - and - and - Yeah. Also why those men in skirts are following Ashya around, exactly?